Introduce configure options for bash-completion, doc, fonts, and icons
This patch introduces the --enable-bash-completion, --enable-doc,
--enable-fonts, and --enable-icons configuration options to control the
build of bash-completion, documentation, fonts, and icons respectively.
This is useful for users of systems such as Gentoo which allow custom
configuration of packages, or for package maintainers in general who
would like finer control over the components built when compiling
Chocolate Doom.